/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jacky.lanlan.song.util.builder;

/**
 * <p>
 * Assists in implementing {@link Object#equals(Object)} methods.
 * </p>
 * 
 * <p>
 * This class provides methods to build a good equals method for any class. It
 * follows rules laid out in <a
 * href="http://java.sun.com/docs/books/effective/index.html">Effective Java</a> ,
 * by Joshua Bloch. In particular the rule for comparing <code>doubles</code>,
 * <code>floats</code>, and arrays can be tricky. Also, making sure that
 * <code>equals()</code> and <code>hashCode()</code> are consistent can be
 * difficult.
 * </p>
 * 
 * <p>
 * Two Objects that compare as equals must generate the same hash code, but two
 * Objects with the same hash code do not have to be equal.
 * </p>
 * 
 * <p>
 * All relevant fields should be included in the calculation of equals. Derived
 * fields may be ignored. In particular, any field used in generating a hash
 * code must be used in the equals method, and vice versa.
 * </p>
 * 
 * <p>
 * Typical use for the code is as follows:
 * </p>
 * 
 * <pre>
 * public boolean equals(Object obj) {
 * 	if (obj instanceof MyClass == false) { return false; }
 * 	if (this == obj) { return true; }
 * 	MyClass rhs = (MyClass) obj;
 * 	return new EqualsBuilder().appendSuper(super.equals(obj)).append(field1,
 * 			rhs.field1).append(field2, rhs.field2).append(field3, rhs.field3)
 * 			.isEquals();
 * }
 * </pre>
 * 
 * @author <a href="mailto:steve.downey@netfolio.com">Steve Downey</a>
 * @author Stephen Colebourne
 * @author Gary Gregory
 * @author Pete Gieser
 * @author Arun Mammen Thomas
 * @since 1.0
 * @version $Id: EqualsBuilder.java 437554 2006-08-28 06:21:41Z bayard $
 */
public class EqualsBuilder {

	/**
   * If the fields tested are equals. The default value is <code>true</code>.
   */
	private boolean isEquals = true;

	/**
   * <p>
   * Constructor for EqualsBuilder.
   * </p>
   * 
   * <p>
   * Starts off assuming that equals is <code>true</code>.
   * </p>
   * 
   * @see Object#equals(Object)
   */
	public EqualsBuilder() {
		// do nothing for now.
	}

	// -------------------------------------------------------------------------

	/**
   * <p>
   * Adds the result of <code>super.equals()</code> to this builder.
   * </p>
   * 
   * @param superEquals
   *          the result of calling <code>super.equals()</code>
   * @return EqualsBuilder - used to chain calls.
   * @since 2.0
   */
	public EqualsBuilder appendSuper(boolean superEquals) {
		if (isEquals == false) { return this; }
		isEquals = superEquals;
		return this;
	}

	// -------------------------------------------------------------------------

	/**
   * <p>
   * Test if two <code>Object</code>s are equal using their
   * <code>equals</code> method.
   * </p>
   * 
   * @param lhs
   *          the left hand object
   * @param rhs
   *          the right hand object
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(Object lhs, Object rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		Class<?> lhsClass = lhs.getClass();
		if (!lhsClass.isArray()) {
			// The simple case, not an array, just test the element
			isEquals = lhs.equals(rhs);
		} else if (lhs.getClass() != rhs.getClass()) {
			// Here when we compare different dimensions, for example: a boolean[][]
      // to a boolean[]
			this.setEquals(false);
		}
		// 'Switch' on type of array, to dispatch to the correct handler
		// This handles multi dimensional arrays of the same depth
		else if (lhs instanceof long[]) {
			append((long[]) lhs, (long[]) rhs);
		} else if (lhs instanceof int[]) {
			append((int[]) lhs, (int[]) rhs);
		} else if (lhs instanceof short[]) {
			append((short[]) lhs, (short[]) rhs);
		} else if (lhs instanceof char[]) {
			append((char[]) lhs, (char[]) rhs);
		} else if (lhs instanceof byte[]) {
			append((byte[]) lhs, (byte[]) rhs);
		} else if (lhs instanceof double[]) {
			append((double[]) lhs, (double[]) rhs);
		} else if (lhs instanceof float[]) {
			append((float[]) lhs, (float[]) rhs);
		} else if (lhs instanceof boolean[]) {
			append((boolean[]) lhs, (boolean[]) rhs);
		} else {
			// Not an array of primitives
			append((Object[]) lhs, (Object[]) rhs);
		}
		return this;
	}

	/**
   * <p>
   * Test if two <code>long</code> s are equal.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>long</code>
   * @param rhs
   *          the right hand <code>long</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(long lhs, long rhs) {
		if (isEquals == false) { return this; }
		isEquals = (lhs == rhs);
		return this;
	}

	/**
   * <p>
   * Test if two <code>int</code>s are equal.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>int</code>
   * @param rhs
   *          the right hand <code>int</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(int lhs, int rhs) {
		if (isEquals == false) { return this; }
		isEquals = (lhs == rhs);
		return this;
	}

	/**
   * <p>
   * Test if two <code>short</code>s are equal.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>short</code>
   * @param rhs
   *          the right hand <code>short</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(short lhs, short rhs) {
		if (isEquals == false) { return this; }
		isEquals = (lhs == rhs);
		return this;
	}

	/**
   * <p>
   * Test if two <code>char</code>s are equal.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>char</code>
   * @param rhs
   *          the right hand <code>char</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(char lhs, char rhs) {
		if (isEquals == false) { return this; }
		isEquals = (lhs == rhs);
		return this;
	}

	/**
   * <p>
   * Test if two <code>byte</code>s are equal.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>byte</code>
   * @param rhs
   *          the right hand <code>byte</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(byte lhs, byte rhs) {
		if (isEquals == false) { return this; }
		isEquals = (lhs == rhs);
		return this;
	}

	/**
   * <p>
   * Test if two <code>double</code>s are equal by testing that the pattern
   * of bits returned by <code>doubleToLong</code> are equal.
   * </p>
   * 
   * <p>
   * This handles NaNs, Infinities, and <code>-0.0</code>.
   * </p>
   * 
   * <p>
   * It is compatible with the hash code generated by
   * <code>HashCodeBuilder</code>.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>double</code>
   * @param rhs
   *          the right hand <code>double</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(double lhs, double rhs) {
		if (isEquals == false) { return this; }
		return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
	}

	/**
   * <p>
   * Test if two <code>float</code>s are equal byt testing that the pattern
   * of bits returned by doubleToLong are equal.
   * </p>
   * 
   * <p>
   * This handles NaNs, Infinities, and <code>-0.0</code>.
   * </p>
   * 
   * <p>
   * It is compatible with the hash code generated by
   * <code>HashCodeBuilder</code>.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>float</code>
   * @param rhs
   *          the right hand <code>float</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(float lhs, float rhs) {
		if (isEquals == false) { return this; }
		return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
	}

	/**
   * <p>
   * Test if two <code>booleans</code>s are equal.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>boolean</code>
   * @param rhs
   *          the right hand <code>boolean</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(boolean lhs, boolean rhs) {
		if (isEquals == false) { return this; }
		isEquals = (lhs == rhs);
		return this;
	}

	/**
   * <p>
   * Performs a deep comparison of two <code>Object</code> arrays.
   * </p>
   * 
   * <p>
   * This also will be called for the top level of multi-dimensional, ragged,
   * and multi-typed arrays.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>Object[]</code>
   * @param rhs
   *          the right hand <code>Object[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(Object[] lhs, Object[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>long</code>. Length and all values are
   * compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(long, long)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>long[]</code>
   * @param rhs
   *          the right hand <code>long[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(long[] lhs, long[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>int</code>. Length and all values are
   * compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(int, int)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>int[]</code>
   * @param rhs
   *          the right hand <code>int[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(int[] lhs, int[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>short</code>. Length and all values
   * are compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(short, short)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>short[]</code>
   * @param rhs
   *          the right hand <code>short[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(short[] lhs, short[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>char</code>. Length and all values are
   * compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(char, char)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>char[]</code>
   * @param rhs
   *          the right hand <code>char[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(char[] lhs, char[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>byte</code>. Length and all values are
   * compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(byte, byte)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>byte[]</code>
   * @param rhs
   *          the right hand <code>byte[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(byte[] lhs, byte[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>double</code>. Length and all values
   * are compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(double, double)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>double[]</code>
   * @param rhs
   *          the right hand <code>double[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(double[] lhs, double[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>float</code>. Length and all values
   * are compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(float, float)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>float[]</code>
   * @param rhs
   *          the right hand <code>float[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(float[] lhs, float[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Deep comparison of array of <code>boolean</code>. Length and all values
   * are compared.
   * </p>
   * 
   * <p>
   * The method {@link #append(boolean, boolean)} is used.
   * </p>
   * 
   * @param lhs
   *          the left hand <code>boolean[]</code>
   * @param rhs
   *          the right hand <code>boolean[]</code>
   * @return EqualsBuilder - used to chain calls.
   */
	public EqualsBuilder append(boolean[] lhs, boolean[] rhs) {
		if (isEquals == false) { return this; }
		if (lhs == rhs) { return this; }
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
   * <p>
   * Returns <code>true</code> if the fields that have been checked are all
   * equal.
   * </p>
   * 
   * @return boolean
   */
	public boolean isEquals() {
		return this.isEquals;
	}

	/**
   * Sets the <code>isEquals</code> value.
   * 
   * @param isEquals
   *          The value to set.
   * @since 2.1
   */
	protected void setEquals(boolean isEquals) {
		this.isEquals = isEquals;
	}
}
